kWh

Every once in a while I’m dragged into a data center power discussion, especially if I’ve prepared a big configuration or if the system needs to be placed in a data center that is pretty stressed power-wise. In most of those conversations it’s only a matter of time until someone starts mixing up the units: kW vs kWh. Since they both mean something completely different, it’s important to use the correct one.

Let’s dive right in. When IT people talk about power they usually intend to use kW (kilowatt). kW is a unit of power. Unfortunately they often use kWh (kilowatt hour) which is a unit of energy. Let’s apply this on an analogy that most IT guys can relate to: cars. Power is measured in bhp or kW, energy is measured in…. gallons of fuel that can fit in the fuel tank!
So if you are one of those people that mixes up the units: Congratulations, you’ve just sent me an email that is the equivalent of telling me your flashy red sports car has 60 liters of gasoline worth of energy. Exciting!